Random PWM Inverter Control Strategy And Its Application On Motor Driver System

In industrial applications of the PWM systems, power electronicstechnology is already an integral part of them, and electromagnetic magneticinterference (EMI) and electronic magnetic pollution caused by power electronicdevices has become a major source of harmonics. In the common used PWMpower electronic systems, their work may be a periodic pulse waveform series.We can analysis the system from the spectrum. As we all know, there are prolifichigh harmonics in square-wave signal, and the spectrum of the high harmonicsreach up to much1000times than the frequency of the square wave. Thus, thecommonly used PWM power electronic system is a strong broadbandelectromagnetic emission source, and the more the frequency is, the greatersevere the power of electromagnetic emissions.Firstly, this paper illustrates the random PWM control theory and themethod of generating random signals and analyses the random pulse function andits power spectral density; then based on two sates Markov chain random PWMsystem model and traditional PWM system was established, finally the paperverifies the theoretical analysis by using PSPICE simulation software.Taking into account of the impact on the inverter output signal due to thedead time, this paper analysise the effects of dead time on three-phase PWMinverter output voltage fundamental waveform, and study the impact of settingdead time on the output voltage and common-mode voltage when inverter workon unload and inducture load respectively. Finally, the paper propose thecompensation way of using random PWM control strategy to reduce the low-order harmonics generated signals caused by the dead time.At last, the paper verifies analysis of random PWM control strategy in theFrequency Control System on the original experimental platform PWM inverter.